Japan's ruling Democratic Party unveiled its party platform and referenced a possible tax hike in Tokyo on Thursday.

Japan has a huge public debt already twice the size of the economy. Prime Minister Naoto Kan has made fixing state finances a top priority and touched on doubling the sales tax rate from its current level of 5 percent.

[Naoto Kan, Japanese Prime Minister]:
"In terms of a clear target rate, we would like to set 10 percent as a reference for now, also given by the Liberal Democratic Party.”

The Democrats, who swept to power last year, have a huge majority in parliament's more powerful lower house. The party will run the government despite who wins the upper house poll. But the party needs an upper house majority to enact laws smoothly.

The Democrats have pledged not to raise Japan's 5 percent sales tax before the next general election for the lower house.

They have stated they will include a plan to set up a non-partisan body to discuss tax reforms.

[Naoto Kan, Japanese Prime Minister]:
"We are considering a thorough multi-partisan debate, but if that doesn't work then the Democratic Party of Japan will become the center of the decision-making process instead of pushing the discussion aside forever.”

Although discussion of sales tax hikes were once viewed as something they were strongly against at election time, surveys have shown that voters have become less resistant to a sales tax increase.